Fertilizer and process of making the same.



SPENCER BLJVEWBERRY, or BAYBRIDGE, OHIO, assrenon or ONE-HALF T0 GEORGE B. FISHBURNE, or CHARLESTON, sou'rrr CAROLINA.

FERTILIZER, AND PROCESS 0E MAKING THE SAME.

No Drawing.

Specification of Letters Patent.

Patented Oct. 11, 1910.

Application filed March 3, 1909. Serial No. 481,203.

This well known that the phosphate of lime contained in native phosphate rock, apatite, bones, etc., is present in these materials in an insoluble form, and is not available forabsorption by plants until converted into soluble form by chemical treatment. The process almost universally followed. is that. of treatment with sulfuric acid.

I have found that the insoluble phosphate of lime contained in natural phosphates,- under which term I include phosphate rock, apatite and bone phosphate,-'-may be rendered completely or almost completely soluble by calcination with a comparatively small proportion of hfosphoric acid or of a water soluble phosp ate such as phosphate of soda or phosphate of otash. Owin to the tendency of phosphoric acid to volati ize at high tem eratures I prefer to use phosphate of so a or of potash. Either monophosphate, diphosphate, or tri-phosphate may be used, and these are practically eqpally efiicient when used in equal quantity. T ese phosphates of soda or potash may be made advantageously from native phosphates of lime or phosphates of alumina and iron, by rocesses which form no part of the inventlon herein. described. I find that to convert all the phosphate of lime contained in the natural phosphate into citrate soluble form, an amount of anhydrous phosphate of soda or phosphate of potash, equal to from'25 to 40 per cent. by Weight of the total phosphate of lime contained in the natural phosphate is required. The effect of this addition is not only to render the phos phate of lime soluble, but also to materially increase the percentage of total phosphoric acid over that contained in the natural phos-. phate, thus giving the product a considerably greater commerclal and fertilizing 'made, under the name of value. For example, 100 parts by weight of a phosphate rock containing per cent. phosphate of lime or 27.5 per cent. phosphoric acid, (P 0 Will require 15 to 25 parts of anhydrous phosphate of soda or phosphate of potash, and if 20 arts anhydrous sodium phosphate, (HNa O are used. the

product of calcination will contain'37.5 per cent. soluble phosphoric acid, (P 0 The amount of additional phosphoric acid re.- quired to render soluble all the phosphate of lune present is approximately that theoretically necessary to form di-calcium phosphate, according to the reaction Ca, (P0 +H PO BCaHPO In the case of phosphate of soda or phosphate of potash, the hydrogen of the di-calcium phosphate is doubtless more or less completely replaced by sodium or potassium, forming as typical compounds CaNaPO and CaKPO respectively. These comounds are however not known in a pure or ree state, and their formation is therefore only suggested as a hypothesis. Assuming such formation, the reaction in the case of ordinary sodium phosphate would be C t (P04) 2+ 2 4= CaHPO +2GaNaPO This equation would require 45.8 parts of anhydrous sodium phos hate to 100 parts phosphate. of lime, and have found that practically complete solubility results from the use of a considerably less quantity, viz., from 25 to 40 per cent, as prevlously stated. I am aware that a product of similar high percentage of soluble phosphoric acid is double su erphosphate, b dissolving natural p os phates in sultiiric acid and treating raw bone phosphates, guano, etc., with' the phos phoric acid solution so obtained. It is wellknown, however, that phosphate rock or apatite is but little acted on by phosphoric acid in solution, while the method of calcination with phosphoric acid or alkaline phosphates herein described is effective when applied to such insoluble natural phosphates, and also the low-grade phosphate rock which cannot profita ly be used in making superphosphate or double superphosphate by the sulfuric acid process.

An illustration of thepractical working dry powder, or by grinding with the natural phosphate, or by adding solution of phosphate of soda or phosphate of potash to the ground natural phosphate. The materials are well mixed, and calcined at a bright orange or nearly white heat, in kilns similar to those used in cement burning, and at a temperature approximately equal to that employedin that industry. The calcined material, which is discharged from the kiln in rather soft balls or grains, is ground to fine powder, and is then in condition to be used as fertilizer or as an ingredient of commercial fertilizers.

By the above described process I obtain a product rich in phosphoric acid, in which all but an insignificant part of the phosphoric acid is soluble in ammonium citrate solution and therefore in condition to be readily absorbed from the soil in the process of plant growth. This product is superior to ordinary commercial superphosphate obtained by the sulfuric acid process on account of its higher content of phosphoric acid, and the fact that the phosphoric acid contained in it, while gradually soluble in the acids of the soil and absorbable by plants, is not soluble in water, and therefore not readily leached out and carried away by the percolation of water through the soil.

Having thus described my invention, what I claim and desire to protect by Letters Patent is as follows:

1. The process of conversion of insoluble phosphate of lime into citrate soluble form by calcination with alkaline stantially as described.

2. The process of making fertilizer, which consists in calcining natural phosphates with alkaline phosphate, substantially as described.

3. The herein described process of making citrate soluble phosphate which consists in calcining an insoluble phosphate of lime With a water soluble phosphate.

4. The herein described process of making citrate soluble phosphate which consists in calcining natural phosphate with a water soluble phosphate.

5. The herein described process of making citrate soluble phosphate which consists in calcinin an insoluble phosphate witha water-solutfie salt of phosphorlcacid.

6. A fertilizing material consisting essentially of phosphate of lime rendered citrate soluble by calcination with alkaline phosphate, substantially as described.

7. A fertilizing material oonsistin essentially of calcium phosphate enriched in phosphoric acid by calcination with alkaline phosphate, substantially as described.

8. A fertilizing material, containing as its essential constituent di-calcium phosphate, HGaPO in which the hydrogen is more or less completely replaced by sodium or potassium, substantially as described.

9. A fertilizing material consisting of a calcined mixture of phosphate of lime and alkaline phosphate.

In testimony whereof I aflix my signature in presence of two witnesses.

SPENCER B. NEWBERRY.

Witnesses:

P. B. BEERY, Arum KUBAGH.

phosphate, sub- 

